Manufacture of artificial filaments, threads, and films



Fatented se i. il, 192 3.

WILFRED PALMER AND WILLIAM ALEXANDER DICKIE, F SPONDON, NEAR DERBY, ENGLAND, ASSIG-NORS TO HENRY DEEYFUS, 01E LONDON, ENGLAND.

No Drawing.

To all whom it may concern:

Be it known that'we, CHARLES WILFRED PALMER and WILLIAM ALEXANDER 'DIGKIJ'J, sub'ects of the King of Great Britain, both of pondon, near Derby, England, have invented certain new and useful Improvements Relating to the Manufacture of Artificial Filaments, Threads, and Films, of which the following) is a specification.

It has een proposed to manufacture artificial filaments and films from solutions of cellulose acetate in organic solvents thatare soluble in or miscible with water, icy-squirt ing or extruding the cellulose acetate solut-ions into aqueous coagulating baths.

Hitherto it has not been possible to obtain strong and elastic filaments or films by such methods owing to the fact that the cellulose acetate is not coa lated by Water in the form of a structura y continuous gel, but with a discontinuous granular or reticulated internal structure, so that the result ing threads or films are lacking in strength and elasticity.

In the specification of another application for patent Serial No. 523,758, filed December 19, 1921 we have roposed, with a view of obviating this di culty to add ammonium thiocyanate or other thiocyanates to the coagulating baths, it having been found that said thiocyanates are capable, owing to a latent solvent power which they 'have for cellulose acetate, of exerting a swelling and coagulation controlling action on the coagulating filaments or-films and thereby tending to preserve continuity of structure and to revent the too complete shrinkage of the cel ulose acetate which ordinarily occurs as the result of the removal of the organic solvent by the aqueous coagulatingbath and causes precipitation of the cellulose acetatewith a discontinuous structure.

According. to the present invention we employ in the aqueous coagulating bath, solvents or latent solvents of cellulose acetate which are soluble in or otherwise miscible with water. We have found that such sub stances have a swelling and coagulation controlling elfect on the cellulose acetate extruded into aqueous coagulating baths containing them. Such solvents .or latent solvents are hereinafter referred to as swelling and coagulation controlling agents.

As examples of such swelling and coagu-- lation controllingeagents may be mentioned,

mmrac'ronn QF-AR'IIFICIAL rrnmrmrs, 'rnnmns, AND runs.

K Application filed December 20, i921. Serial No. 523,759.

acetone, diacetone alcohol, acetic acid, or

formic acid, or mixtures of any of these, also aqueous solutions of zinc chloride or other salts" which like the thiocyanateshave a latent solvent power for cellulose acetate.

to the present invention we- Accordin add the swe ling and coagulation controlling agents to the coagulation baths.

The invention applies in particular to the manufacture. of artificial filaments, threads, or films from acetone-soluble cellulose acetates, but-may also be employed with other acetates of cellulose.

The solvents or' latent solvents employed as swelling and controlling agents according to the invention must be used. in sufli- .umrao srras rarer oFFzc.

cient quantity or concentration to exert the requlred modifying influence on the shrlnking action of the water, but not in such quantity or concentration as to exert too great a solvent power and prevent coagulation of the cellulose acetate.

In carrying out the invention, solutions of cellulose acetate in any organic solvents miscible with water or soluble in water may be employed, for example acetone, or acetone-alcohol mixtures.

In carrying out the invention we may work for instance as follows, it being understood that this example is given by way of illustration only and 1s in no way limitativ'e.

A 16 per cent solution of cellulose acetate in acetone is forced in the known way through the capillary orifices of spinning nozzles into an aqueous bath containing-a suitable quantity of acetone, diacetone alcohol, alcohol, or other solvent or latent solvent for example about 10-50 parts of acetone, or about 100 parts of alcohol, orabout 5 parts of diacetone alcohol or acetic acid, .per 100 parts of water.

The coagulated filaments are carried through the bath under a guide and are wound up continuously in any known way. The swelling agent carried forward in the thread is removed by washing, and the pur1- fied threads of cellulose acetate are dried.

The filaments issuing from the, squirting nozzle are endowed with considerable strength and the combined action of the water and swelling agent are such that the cellulose acetate solutions may be drawn out to filaments of great tenuity from orifices of relatively large diameter. In this way it is possible to obtain artificial silk filaments of very low denier, for example as fine as 1 or 2 denier, i. e. as fine as natural silk.

It is understood that the limits of con centration of the swelling and coagulation controlling agent may be varied to suit desired conditions.

What we claim and desire to secure by Letters Patent is z- 1. In a process for the manufacture of filaments, threads or films, extruding cellulose acetate in solution into an aqueous coagulating bath containing an agent capable of swelling and controlling coagulation of the cellulose. acetate, said agent being miscible with water.

2. In a process for the manufacture ,of filaments, threads or films, extruding a solution comprising cellulose acetate and an organic solvent thereof miscible with water, into an aqueous coagulating bath containing an agent capable of swelling and controlling c0- agulation of the cellulose acetate, said agent being miscible with Water.

3. In a process for the manufacture of filaments, threads or films, extruding a solution of cellulose acetate in acetone into an aqueous coagulating bath containing acetone.

In testimony whereof We have hereunto subscribed. our names.

CHARLES WILFRED PALMER. WILLIAM ALEXANDER DIOKIE. Witnesses:

THOS. HrCoon, A. 'A. GUNNING. 

